Patent GB-538577-A (GB)
Title: Improvement in commercial phonographs
IPC: G11B3/34
Filed: 1940-06-20
Abstract: 538,577. Phonographs. DICTAPHONE CORPORATION. June 20, 1940, No. 10628. Convention date, Aug. 1, 1939. [Class 40 (ii)] Relates to dictating machines having a soundbox carriage capable of forward and backspace movements alongside a cylindrical mandrel and a sound-box provided with recording and reproducing styli and capable of being set in recording, or reproducing, or neutral position. According to the invention, means are provided tending to shift the sound-box in a predetermined cyclic order to its several positions, manually controlled stopping means are provided to stop the sound-box in successive positions, and means operable upon predetermined changes in the operation of the machine are provided to release the stopping means. Reference is made to U.S.A. Specification 2,152,586 as a prior example of more or less automatic controlling devices for a dictating machine. General lay-out.-The dictating machine is generally arranged as shown in Fig. 1, with a cylindrical mandrel 12 and a sound-box carriage 14 over a base 10, an angular casing 20 containing the driving mechanism, and a cradle 25 for the mouth-piece 28 of the speaking-tube 30. Mandrel and driving mechanism.-The mandrel shaft 15, Fig. 5, is supported at its left-hand in a bearing 121 and is keyed by a pin 125 to a sliding clutch sleeve 124 adapted to be moved in and out of engagement with a clutch member 119 on a pulley 118 driven by a belt 21, Fig. 2, from a motor 11. The motor circuit is controlled by a switch 195, Fig. 6, normally held open when a plunger 24 attached to the cradle 25, Fig. 1, is depressed by the weight of the mouth-piece 28. When the mouth-piece is lifted, the plunger 24 is raised by a spring 192, and a toggle spring 199 causes a switch lever 197 to swing on its pivot 198 and bridge the contacts at the ends of the conductors 193, 194, thereby starting the motor. The clutch sleeve 124 is operated by a yoke 127 keyed by a stem 129, Fig. 20, and a spring 130 to a horizontal crossshaft 128 provided with an arm 133 controlled by a spring 103, Fig. 20, and a Bowden-wire mechanism 134 connected to a bell-crank lever 140 on the sound-box carriage, which lever is operated by a plunger 144 connected by another Bowden-wire mechanism 145 to a thumb button 23 on the mouth-piece 28. Sound-box carriage mechanism.-The soundbox carriage 14, Figs. 1, 2 and 9, is slidably mounted and guided on rods 16, 36, and is provided with a nut plunger 52 adapted to be urged by a spring into engagement with a feed screw 44 within the rod 16. The plunger can be withdrawn by a manually operated lever 72 on a sleeve 70 provided with an arm 68 adapted to bear on a lever 62 which is pivoted at 64 and passes through a slot in the plunger 52. The left end of the feed screw 44 is journalled in a bearing 48, Fig. 5, and is keyed by a pin 157 to a sliding clutch sleeve 156 which can be moved as described below to engage either gear wheel 152 or gear wheel 167 both loose on the feed screw shaft. The gear wheel 152 is in mesh with a pinion 151 fast with another pinion 150 rotatable about a sleeve 162 ; and the pinion 150 is in mesh with a pinion 147 rotatable on a stud 148 and in mesh with a pinion 146 cut in the mandrel shaft 15. This train of gearing serves to drive the carriage in a forward direction, i.e. to the right. The other gear wheel 167 is in mesh with a pinion 168 fast with a gear wheel 169, itself in mesh with a pinion 120 fast with the pulley 118 driven by the motor 11. This train of gearing serves to drive the carriage backward, i.e. to the left. Advance marker.-This marker 206, Fig. 9, comprises two plates 210, 211 guided along a bar 209, formed on one side with rack teeth held by a flat spring on 214 on the other side in engagement with a pinion 213 journalled in the plates 210, 211. The pinion 213 is fast with a ratchet wheel 216 co-operating with a pawl 217 integral with a sleeve 11 keyed to, but slidable on, a shaft 112. During forward movement of the carriage towards the right, a set screw 207 on the carriage bears against a stud 208 on the marker, whereby the marker follows the forward movement. When the carriage is moved back, the pawl 217 prevents backward rotation of ratchet wheel 216, and the marker remains in its advanced position. Sound-box mechanism.-The sound-box 90, Fig. 9, is attached to a tone-tube 88 connected to a telescopic tube 86 by a ball-and-socket joint 84 pivoted at 85 to a sleeve 83 pivoted at 82 in a slide 80 in the carriage casing 78. The slide 80 is operated by a lever 96 pivoted at 98 and provided with rollers 108 embracing a heart-shaped cam 100 on a sleeve 113 slidable on a shaft 111 but keyed thereto for rotation, so that at any position of the carriage, a rotation of the shaft 111 can operate the cam 100. The shaft 111 with the cam 100 rotates always in the same direction and this is adapted to place the sound-box in three different positions successively, the cycle of positions being repeated for each complete rotation of the shaft. In one position, Fig. 9, the sound-box is in the middle and lifted position, i.e. a neutral position, out of action. In the next position brought about by a third of a revolution of shaft 111, the sound-box will be forward and lowered to engage the reproducing stylus 94 with a record cylinder, and in the third position brought about by a further third of revolution of shaft 111, the sound-box will be backward and lowered to engage the recording stylus 92 with the record cylinder. The lifting and lowering of the sound-box is performed by the co-operation of a cam 102 on the tone-tube 88 with a ledge, which allows the lowering of the sound box only when it reaches the extreme positions for recording and reproducing respectively. This three step cycle of rotation of the shaft 111 is controlled by the following mechanism. The left end of the shaft 111 is keyed to a disc 184, Fig. 5, attached by pins 185 to a disc 174 frictionally gripped between flanges 173, 175 and sleeves 170, 176. The sleeve 170 is keyed to the gear wheel 169 and driven thereby. The sleeve 176 is keyed to the sleeve 170 by a pin 177, but is slidable thereon and is influenced by a coiled spring 179 to grip the disc 174. This disc has one ratchet tooth 183, Fig. 6, adapted to be stopped in turn by three pawls 180, 181, 182. The pawl 180 stops rotation at a point corresponding to the recording position of the sound-box. The next pawl 181 stops rotation at the neutral position of the sound-box. And the third pawl 182 stops rotation at the reproducing position of the sound-box. First pawl 180, Fig. 6.-This pawl is fast on the shaft 110. The sleeve 70, Fig. 9, on the carriage is keyed to the shaft 110 but slidable thereon, and is fitted with a thumb lever 72 by means of which the shaft 110 can be turned to cause the pawl 180 to release the tooth 183, when it is desired to displace the carriage backward or forward by hand, the operation of the thumb lever 72 causing also the disengagement of the carriage from its feed-screw after the deflection of the pawl 180 which resulted in the raising of the sound-box to neutral position. The pawl 180 is moreover provided with an arm 189 fitted with a roller 188 co-operating with the nose 187, Fig. 2, of a back-spacing lever 159 pivoted at 160 and provided with a knob 22, Fig. 1. This lever controls the clutch sleeve 156 and is normally maintained by a spring 161 in the position shown in Fig. 5 with the clutch in engagement with gear wheel 152 for forward drive of the carriage. For automatic backspacing, the lever 159 is moved by hand against the action of spring 161 to shift the clutch into engagement with gear wheel 167. This movement of the lever 159 also causes its nose 187 to deflect the pawl 180 to release the tooth 183. The pawl 180 is also adapted to be deflected to release the tooth when the mouth-piece 28 is placed on its cradle 25, this causing the depression of the spring plunger 24, the pawl being deflected by the co-operation of a lug 190 on the plunger with a roller 191 on: the pawl. Thus, when the pawl 180 is in engagement with the tooth 183, the sound-box is in recording position; and this pawl can be deflected to allow the tooth to pass to pawl 181 to bring sound-box to neutral position by either of three devices, one the thumb lever 72 when hand displacement of carriage is desired, another the back-spacing lever 22, 159 when automatic back-spacing is desired, and a third the cradle plunger 24 whenever the mouth-piece 28 is placed on its cradle. Second pawl 181, Fig. 6.-This pawl, which is adapted to stop the tooth 183 in the neutral position of the sound-box, is connected by a link 201 to an arm 200 on an horizontal cross shaft 128, which is controlled through Bowdenwire devices from a thumb button 23 on the mouth-piece to determine the position of the clutch-sleeve 124 transmitting the drive to the mandrel as described above. This mechanism causes the pawl to release the tooth 183 so long as the thumb-piece 23 is pressed to maintain the drive of the mandrel. The tooth then passes to the third pawl 182, which holds the sound-box in reproducing position. Third pawl 182, Fig. 6.-This pawl is fast on shaft 112 ; and the pawl 217, Fig. 9, co-operating with the ratchet wheel 216 of the advance marker is keyed to the shaft 112 but slidable thereon. When the drive is started by the lifting of mouth-piece 28 and the manipulation of the thumb-piece 23, the tooth 183 is against the pawl 182 and the sound-box in reproducing position. If the advance marker is ahead of the carriage, the sound-box remains in reproducing position until the carriage overtakes the advance marker and begins to drive this forward. The oscillations of the pawl 217 by the ratchet wheel 216 of the advance marker are then transmitted to the pawl 182 which releases the tooth 183 and allows it to pass to the first pawl 180, thereby bringing the sound-box to reproducing position. The